Depth sensing technology can be used to determine a person's location in relation to nearby objects or to generate an image of a person's immediate environment in three dimensions (3D). One application in which depth sensing technology may be used is in head-mounted display (HMD) devices and other types of near-eye display (NED) devices. Depth sensing technology can employ a stereo vision, time-of-flight (ToF) or structured light depth camera. Such a device can create a map of physical surfaces in the user's environment (called a depth image or depth map) and, if desired, to render a 3D image of the user's environment.
A depth sensing system (also referred to as depth imaging system) can include a light source for providing structured light. Structured light is a process of projecting a known pattern of light onto a scene. The light is reflected by the scene and captured by a depth sensing camera ( ). The light pattern captured by the depth sensing camera is different from the original known pattern because of the reflection by the scene, that is, the light pattern captured by the imaging camera is “deformed.” Based on the differences between the deformed pattern and the known original pattern, the depth sensing system can calculate the depth information of the scene. However, the light pattern being captured can be further deformed due to factors other than the scene. For example, a temperature drift of a light source can cause a shift of the light pattern. Such a shift of the light pattern tends to cause systematic bias of the calculated depth information of the scene.